Worcester Bosch control knob resides on one of the spindles on the front of the control panel and allows you to manually control certain aspects of the appliance's functionality. Some boilers let you adjust the temperature, while others even let you modify the existing operation. This means the user can have the boiler offer hot water without the central heating on and vice versa. This Worcester Highflow Control Knob (part number 87161410870) is a hardware handle manufactured by Bosch for Worcester appliances. It allows manual control of aspects like temperature and operation, enabling independent heating and hot water functions.